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Issue A&A
Volume 418, Number 3, May II 2004
Page(s) L39 - L42
Section Letters
DOI http://dx.doi.org/10.1051/0004-6361:20040118



A&A 418, L39-L42 (2004)
DOI: 10.1051/0004-6361:20040118

Letter

VLTI/VINCI observations of the nucleus of NGC 1068 using the adaptive optics system MACAO

M. Wittkowski1, P. Kervella1, 2, R. Arsenault1, F. Paresce1, T. Beckert3 and G. Weigelt3

1  European Southern Observatory, Karl Schwarzschild-Str. 2, 85748 Garching, Germany
2  LESIA, Observatoire de Paris, 92195 Meudon Cedex, France
3  Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany

(Received 8 March 2004 / Accepted 20 March 2004 )

Abstract
We present the first near-infrared K-band long-baseline interferometric measurement of the nucleus of the prototype Seyfert 2 Galaxy NGC 1068 with resolution  $\lambda/B \sim$ 10 mas obtained with the Very Large Telescope Interferometer (VLTI) and the two 8.2 m diameter Unit Telescopes UT 2 and UT 3. The adaptive optics system MACAO (Multi Application Curvature Adaptive Optics) was employed to deliver wavefront-corrected beams to the K-band commissioning instrument VINCI. A squared visibility amplitude of 16.3 $\pm$ 4.3% was measured for NGC 1068 at a sky-projected baseline length of 45.8 m and azimuth angle 44.9 deg. This value corresponds to a FWHM of the K-band intensity distribution of 5.0 $\pm$ 0.5 mas (0.4 $\pm$ 0.04 pc at the distance of NGC 1068) if it consists of a single Gaussian component. Taking into account K-band speckle interferometry observations (Wittkowski et al. 1998; Weinberger et al. 1999; Weigelt et al. 2004), we favor a multi-component model for the intensity distribution where a part of the flux originates from scales clearly smaller than ~5 mas ( $\la$0.4 pc), and another part of the flux from larger scales. The K-band emission from the small ( $\la$5 mas) scales might arise from substructure of the dusty nuclear torus, or directly from the central accretion flow viewed through only moderate extinction.


Key words: techniques: interferometric -- galaxies: nuclei -- galaxies: Seyfert -- galaxies: individual: NGC 1068

Offprint request: M. Wittkowski, mwittkow@eso.org

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